Any Flour is not an actual in-game-object but a generic term referring to one of the following 2 game-objects: Barley Flour, Wheat Flour.
Crafting recipes requiring Any Flour can be made from either type of flour, or even from a combination of both. The type of flour used has an effect on the FEP values of the food being prepared.

Flour can be stored in a Granary or a Barrel, but the two different types of flour cannot share the same barrel or occupy the same slot in a granary.